<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* 后代选择器 */
    .home span {
      color: red;
      font-size: 30px;
    }

    /* .home的子代的span元素设置一个背景 */
    .home > span {
      background-color: green;
    }
  </style>
</head>
<body>
  
  <div class="home">
    <span>啦啦啦啦</span>  
    <div class="box">
      <p>我是p元素</p>
      <span class="home-item">呵呵呵呵</span>
    </div>

    <div class="content">
      <div class="desc">
        <p>
          <span class="home-item">哈哈哈哈</span>
        </p>
      </div>
    </div>
  </div>

  <!-- 不希望被选中 -->
  <span>嘻嘻嘻</span>
  <div>
    <span>嘿嘿嘿</span>
  </div>

</body>
</html>